In the Fundamentals we mentioned the Curse of Knowledge, and six ways to overcome it.
My personal favorite, though, isn’t on that list. It is:
#7: Ask questions.
Specifically, ask your audience to describe back to you what you just said.
Ask them to describe your world back to you, and see how close they get. If they get it right, or at least almost right, your explanation was fairly clear.
Plus, there’s the added benefit that what other people see is almost never exactly what you see, so, in listening to their explanation, you might learn a new way to see your own world.